import math

# Press the green button in the gutter to run the script.
if __name__ == '__main__':
    size = input()
    size = int(size)
    input = input()
    prvky = []
    result = 0
    for char in input:
        prvky.append(char)

    x = 1
    while size > (x+2)**2:
        x += 1
    for i in range(1, x+1):
        celkovy_size = (i+2)**2
        for j in range(0, size, i):
            operacni_mnozina = prvky[j:celkovy_size+1]
            modre = operacni_mnozina.count('X')
            cervene = operacni_mnozina.count('O')
            if modre > cervene:
                if cervene >= i**2 and modre >= (celkovy_size-(i**2)):
                    result += 1
            else:
                if modre >= i**2 and cervene >= (celkovy_size-(i**2)):
                    result += 1
    print(result)